| Description | Span date of drawings: 1778-1864
Dates of engines ordered: 1782-1803
Portfolios 1 to 244 contain drawings for engines that employed the sun and planet gear. The sun and planet gear was a mechanism for converting the reciprocating motion of the engine beam into rotative motion to power textile mills, grindstones, tilt hammers, rolling mills etc. Watt developed the sun and planet gear as an alternative to the crank, as there were technical advantages in using the sun and planet gear and fly wheels to generate rotative motion, and also as the crank was the subject of a patent taken out by James Pickard, dated 23 Aug. 1780. Watt included the sun and planet gear in his patent of 13 Feb. 1782, and the majority of sun and planet engines were built between 1784 and 1800. Pickard's patent expired in 1794, but Boulton & Watt continued to employ the sun and planet gear until around 1803.
Henry Hazleton arranged the portfolios in roughly chronological order, going by the earliest date he could find on the drawings. This arrangement holds for Portfolios 1 to 237, but Portfolios 238 to 244 are out of the chronological sequence. It is unclear why Hazleton left these until the end, but most contain large numbers of drawings or drawings for several engines for the same customer. Hazleton also amalgamated some original Drawing Office Books (portfolios) which contained drawings of different engines for the same customer. For example Portfolio 2 contains drawings for two separate engines for Henry Goodwyn & Co. which came originally from two separate books. However he was not consistent in this; for example Portfolio 63 contains the drawings for the Salford Twist Co.'s first engine, whereas the drawings for their other three engines can be found in Portfolio 242. He listed sun and planet engines in Section A of the Catalogue of Old Engines.
Note that the following portfolios in this series contain drawings for engines that are not sun and planet engines:
5/77: 9 horse power double-acting crank engine, 1795 (for H. P. Whately)
5/239a: "Double Battering Engine", 1778 (for John Wilkinson, not built)
5/239b: "Bradley Coal Engine", 1782 (for John Wilkinson, not built)
5/241c: 8 horse power double-acting crank engine, 1797 (for Hawkesbury Colliery)
5/242c: 100 horse power crank engine, 1800-1801 (for the Salford Twist Co.)
5/242d: 10 horse power crank engine, 1810 (for Philips & Lee)
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